1. Field of the Invention
The present invention relates to contact elements for electrical connectors and electrical connectors having the same.
2. Related Art
Intermediate electrical connectors for connecting two connection objects or circuit boards are well known.
Japanese patent application Kokai No. 4-144083 discloses such a connector. As shown in FIG. 4, a housing 51 is provided with a comb-like guide 52 having a plurality of guide grooves 53 in which contact elements 54 are placed so as to be parallel to the faces of the guide grooves.
The contact elements 54 are stamped from sheet metal so as to have a U-shaped resilient section 55 with a contact portion 56 at a free end and a connection section 57 at the other end. The contact section 56 projects upwardly while the connection section 57 extends downwardly. Opposed edge portions 56A and 57A of the contact and connection sections 56 and 57, respectively, are curved in opposite directions to form contact points. The connection section 57 is connected to a circuit trace of a connection object (not shown) by soldering or the like.
In operation, another connection object (not shown) is pressed against the contact sections 56 to deform the U-shaped resilient sections 55, thereby bringing the opposed edge portions 56A and 57A into contact with each other under a predetermined pressure. Thus, the two connection objects are connected electrically.
However, when the contact points are closed, the spring constant of the resilient sections abruptly rises and the resilient sections are hardly deformed thereafter. Consequently, in order to provide a satisfactory contact area, it is necessary to apply a large force to the connection object.
Since the opposed edge portions of the contact and connection sections are curved in the opposite directions, if there are errors between the contact and connection sections in the thicknesswise direction, the above contact pressure varies with the contact elements. Consequently, poor or uneven contact is produced between the opposed edge portions.
In addition, there is frequently a short-circuit between the contact points of the contact element. In order to provide the resilient section with satisfactory resilience, the resilient sections are made so long that the terminal becomes long.